The extended microbiology of group A streptococcal pharyngitis. Observations during a double-blind controlled study of cephalexin twice versus four-times daily.

In a double-blind controlled study we compared the effectiveness of cephalexin b.i.d. versus q.i.d. in the treatment of group A streptococcal pharyngitis in 65 children. Clinical improvement was noted in 64 patients (98%) and bacteriologic cure in 60 (92%). Despite good compliance, three bacteriologic failures were noted in the q.i.d., and two in the b.i.d. treatment groups. Two of these five were carriers. Significant antibody responses were observed in 61% of the patients by at least one of three tests (ASO, anti-DNase B, Streptozyme). We also investigated the extended microbiology of streptococcal pharyngitis by looking for the presence of viruses, chlamydia and beta-lactamase producing organisms in the pharynx. Respiratory viruses were isolated concomitantly with Streptococcus pyogenes in six patients. Beta-lactamase producing bacteria were present in the pharynx of 98% of the patients at the initiation of treatment and comprised 1-98% of the total bacterial flora. The beta-lactamase producing flora did not significantly change with cephalexin therapy.